EFFECTS OF DIFFERENT STYRENE METABOLITES ON CYTOTOXICITY, SISTER-CHROMATID EXCHANGES AND CELL-CYCLE KINETICS IN HUMAN WHOLE-BLOOD LYMPHOCYTES IN-VITRO

5 metabolites of styrene were tested in vitro for their cytotoxic effe cts, induction of SCEs and changes in cell-cycle progression in cultur ed human blood lymphocytes. Fresh heparinized peripheral blood (0.3 ml ) from normal volunteers was cultured for a total of 72 h in 5 ml of R PMI 1640 medium containing 10% fetal calf serum, 0.1% garamycine, 1% g lutamine and 1% phytohaemagglutinin. Styrene-7,8-oxide (SO), styrene g lycol (SG), phenylglyoxylic acid (PGA), S-[1,2-phenyl-2-hydroxyethyl]- glutathione (PEG) (a glutathione conjugate of styrene oxide), N-acetyl -S-[1,2-phenyl-2-hydroxyethyl]-cysteine (NAPEC) in dimethyl sulfoxide (DMSO) were injected into the cultures 36 h after initial culture, so that the exposure time for these metabolites was 36 h. The final conce ntration of SO was 100 muM and those of the other metabolites were 500 muM. 24 h before harvest, BrdU (10 mug/ml) was added into the culture s for assessing cytogenetic endpoints. SO showed significant induction of SCEs and cell-cycle delay as well as a significant decline of cell survival. The same phenomena, but of less magnitude, were also observ ed with NAPEC, a cysteine derivative of SO. On the other hand, SG, PGA and PEG failed to produce any significant changes of these endpoints compared to the control. Thus, the present results have demonstrated t hat, in addition to SO, NAPEC possesses some cytogenotoxic potential a nd hence, these two metabolites together could contribute to the genot oxicity of styrene in human blood lymphocytes.